This invention relates generally to a mechanism for rotating a shaft of a machine and, more particularly, to a rotary turning apparatus for use in manually rotating the shaft of a steam turbine.
Shafts need to be rotated in machines at slow speeds for a variety of different reasons. For example, some machines, such as compressors or turbines, use hot fluids, such as steam, during their operations. Often these fluids are not evenly distributed throughout the machine. As a result, some sections of these machines heat up more than others. When these machines complete their operations and are shut down, the shafts in these machines stop rotating and the heat stored in the machine begins to heat up the shaft. Since some sections of the machine are hotter than others, the portions of the shaft near those sections begin to heat up more rapidly than other portions of the shaft. Eventually this heating can cause an undesirable bowing of the shaft which can damage both the shaft and other parts of the machine. One technique to avoid this bowing problem is to rotate the shaft slowly as the machine cools to more evenly distribute the heat around the shaft.
Shafts in machines may also need to be rotated at slow speeds so that the machines can be inspected. Often by rotating the shaft, an operator is provided with a better angle to inspect internal components or elements which are mounted on the shaft or are located in the housing.
Several different types of devices have been developed to rotate the shafts of these machines at slow speeds, but each of these prior devices has drawbacks and/or limitations. For example, electric or gas powered systems have been developed to automatically rotate the shafts of these machines at slow speeds. Unfortunately, these systems are often expensive and involve complicated designs. Additionally, these systems often add significantly to the overall size of the machines which may need to fit into relatively tight quarters when in use. Further, the installation of these systems is often difficult and time consuming. Accordingly, there is a need for a simple, inexpensive, and compact apparatus for rotating the shaft of a machine which can be easily installed.
A rotary turning apparatus in accordance with one embodiment of the present invention includes an engagement device with at least one end and a biasing device. The one end of the engagement device is shaped to mate with one end of a shaft. The shaft is mounted for rotation in a housing and is accessible via a passage in a wall in the housing. The biasing device is disposed substantially within the passage in the wall and biases the one end of the engagement device away from engagement with the one end of the shaft. By compressing the biasing device, the end of the engagement device can be mated with the end of the shaft for manual rotation of the shaft.
A machine with a rotary turning apparatus in accordance with another embodiment of the present invention includes a housing with at least one wall, a shaft, a passage extending through the wall, at least one shoulder, a collar, and a biasing device. The shaft is mounted for rotation in the housing. The housing includes at least one passage which extends through the wall and provides access to one end of the shaft. The shoulder is located on the wall in the passage. The engagement device has an end which is shaped to mate with the one end of the shaft and is mounted for movement within the passage. The biasing device is positioned between the shoulder and a collar which extends at least partially around the engagement device. The biasing device biases the one end of the engagement device away from engagement with the one end of the shaft. By compressing the biasing device, the end of the engagement device can be mated with the end of the shaft for manual rotation of the shaft.
A machine with a rotary turning apparatus in accordance with yet another embodiment of the present invention includes a housing with at least one end wall, at least one bearing assembly, a shaft, a passage, a pair of shoulders, an engagement device, a biasing device, and a seal. The shaft is mounted for rotation in the housing and on the bearing assembly. The passage extends through the wall to provide access to one end of the shaft. The engagement device has an end which is shaped to mate with the one end of the shaft and is mounted for movement in the passage between the pair of shoulders which are located on the wall in the passage. The biasing device is positioned between one of the shoulders and the collar which extends at least partially around the engagement device. The biasing device biases the one end of the engagement device away from engagement with the one end of the shaft. By compressing the biasing device, the end of the engagement device can be mated with the end of the shaft for manual rotation of the shaft.
The rotary turning apparatus in accordance with the present invention provides a number of advantages. For example, one advantage of the present invention is the ease with which it can be used. By simply compressing the engagement device into a mating engagement with the shaft and then rotating the engagement device, the shaft of the machine can be rotated. The engagement device is conveniently spring loaded so that when it is not in use, the rotary turning apparatus is biased away from and will not interfere with the normal operation of the rotating shaft. Additionally, the rotary turning apparatus includes a seal to help minimize the loss of any fluid, such as oil, which is located in the housing of the machine.
Another advantage of the present invention is its compact and simple design. The simple design minimizes the number of necessary components and thus minimizes the overall size of the rotary turning apparatus and of the machine it is mounted on. As a result, the design is inexpensive to implement and it is unlikely that the additional size resulting from the inclusion of the present invention in the machine will prevent that machine from fitting into its desired location.
Further, the present invention provides a rotary turning apparatus which is relatively easy to install on new and existing machines. A substantial portion of the rotary turning apparatus is conveniently disposed within the wall of the housing. Not only does this provide a more aesthetically pleasing design, but it also enables new and existing machines to be more easily converted to incorporate the present invention. Basically, to retrofit an existing machine, the existing end wall of the housing is simply replaced with an end wall which incorporates the compactly designed and stored rotary turning apparatus.